Натрия сульфат

Химические свойства

Sodium sulfate, NaS04, also known as thenardite and salt cake, is a crystalline compound that melts at 888°C (1632°C). Sodium sulfate is found in natural form(thenardite) in Chile and Spain. It is used in the manufacture of paperboard, glass,and freezing mixtures. The hydrate, Na2S04·10H20, also known as "Glauber's salt," is a white water-soluble solid formed by heating sodium chloride and sulfuric acid. It is used in dyeing,manufacturing glass,and in the preparation of sodium bisulfate.

Физические свойства

Anhydrous sodium sulfate is a white crystalline powder; orthorhombic or hexagonal structure; hygroscopic; refractive index 1.468; hardness 2.8 Mohs; density 2.664 g/cm³; melts at 884°C; soluble in water, insoluble in ethanol.
The decahydrate consists of colorless monoclinic crystals; refractive index 1.394; hardness 1.8 Mohs; density 1.4 6g/cm³; decomposes at 32°C; soluble in water; insoluble in ethanol.

Вхождение

Sodium sulfate occurs in nature as the minerals mirabilite and thenardite. While thenardite is the anhydrous form of Na²SO⁴, mirabilite is a naturallyoccurring decahydrate, Na₂SO₄?10H₂O.
Sodium sulfate is one of the most important sodium salts. The decahydrate,commonly known as the Glauber’s salt, was first prepared by Johann Glauber in the seventeenth century as a by-product in making hydrochloric acid from sulfuric acid and sodium chloride.
Sodium sulfate is used in manufacturing paper pulp by the Kraft Process. Other uses are in manufacturing glass and ultramarine; in dyeing and printing textiles; as a filler in synthetic detergents; and for standardizing dyes. A major use of anhydrous sodium sulfate is as an agent to remove water from organic solvents and their extracts for organic synthesis and instrumental analysis. Sodium sulfate is a common laboratory reagent. Also, it is used to prepare other sodium salts.

Использование

Sodium sulfate is a filler in the manufacturing of synthetic detergents and soaps and a laboratory reagent. It may enhance the irritant action of certain detergents.

Методы производства

Sodium sulfate is mined from its natural mineral deposits and subjected to purification.
Sodium sulfate is synthesized by the Mannheim process or Hargreaves process. Manheim’s process is based on Glauber’s reaction between sulfuric acid and sodium chloride: 2NaCl + H₂SO₄ → Na₂SO₄ + 2HCl↑
The process was devised by Johann Glauber to produce hydrochloric acid. Sodium sulfate is isolated from the solution by fractional crystallization.
Hargreaves’ process also was developed to produce hydrochloric acid. It is a variation of Mannheim’s method. In this method, sulfur dioxide is used instead of sulfuric acid. The reaction is as follows: 4NaCl + 2SO₂ + O₂ + 2H₂O → 2Na₂SO₄ + 4HCl↑
Sodium sulfate also is obtained as a byproduct of manufacturing phenol by caustic fusion.

Определение

A white crystalline compound, Na₂SO₄, usually known as the anhydrous compound (orthorhombic; r.d. 2.67; m.p. 888°C) or the decahydrate (monoclinic; r.d. 1.46; which loses water at 100°C). The decahydrate is known as Glauber’s salt. A metastable heptahydrate (Na₂SO₄·7H₂O) also exists. All forms are soluble in water, dissolving to give a neutral solution. The compound occurs naturally as
mirabilite (Na₂SO_4·10H₂O),
threnardite (Na₂SO₄), and
glauberite (Na₂SO₄·CaSO₄).
Sodium sulphate may be produced industrially by the reaction of magnesium sulphate with sodium chloride in solution followed by crystallization, or by the reaction of concentrated sulphuric acid with solid sodium chloride. The latter method was used in the Leblanc process for the production of alkali and has given the name salt cake to impure industrial sodium sulphate. Sodium sulphate is used in the manufacture of glass and soft glazes and in dyeing to promote an even finish. It also finds medicinal application as a purgative and in commercial aperient salts.

Общее описание

Sodium sulfate (Na₂SO₄) can be obtained directly via precipitation from a saturated solution of Na₂SO₄ at room temperature (20°C). Its crystallization and growth rates at room temperature (20°C) under various conditions have been investigated. Sodium sulfate can be produced during Leblanc process, from sodium chloride and sulfuric acid.

Профиль безопасности

Moderately toxic by intravenous route. Mildly toxic by ingestion. An experimental teratogen. Experimental reproductive effects. Questionable carcinogen with experimental tumorigenic effects. Violent reaction with Al. When heated to decomposition it emits toxic fumes of SOx and Na2O. See also SULFATES.

Возможный контакт

Sodium sulfate is used in the manufacture of glass; as a precipitating agent in the manufacture of silver emulsions; as an analytical reagent; in making ultramarine and paper pulp; in ceramic glazes and pharmaceuticals; as a food additive; and a filler in synthetic detergents.

Описание

Натрия сульфат-Представляет собой сыпучие, гигроскопические, бесцветные кристаллы или мелкий белый кристаллический порошок, с горьким соленым вкусом, без запаха. Превращается в кристаллогидрат, активно впитывая влагу из воздуха, при комнатной температуре. Практически не растворяется в метиловом и этиловом спиртах. Легко растворяется в воде и глицерине. Сульфат натрия можно встретить в природе в виде минерала тенардита либо в виде кристаллогидрата мирабилита.

Химические свойства

Натрий сернокислый или Натрий сульфат безводный — бесцветный кристаллический порошок, кристаллизуется из водных растворов выше 32,384 °С. Плохо растворим в водно-спиртовых средах; растворимость при 20 °С в этаноле 0,439% по массе, метаноле-2,40%.

Применение

Натриевые соли серной кислоты в медицине применяются или применялись в качестве слабительных, антацидных средств и минерально-витаминных комплексов.
Сульфаты натрия включаются в состав лекарств, как вспомогательные вещества.

Производство

Промышленный способ получения сернокислого натрия получается в процессе взаимодействия хлорида натрия с серной кислотой в специальных «сульфатных» печах при температуре 500—550°C, при этом одновременно получается хлороводород.

Перевозки

UN2630 Selenates or Selenites, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Методы очистки

Crystallise sodium sulfate from water at 30o (1.1mL/g) by cooling to 0o. It becomes anhydrous at 32o.

Несовместимости

Violent reaction with aluminum, magnesium. Attacks metals in the presence of moisture.

Утилизация отходов

Do not discharge waste sodium sulfate directly into sewers or surface waters. Recovered sodium sulfate may be disposed of by burial in a landfill.